We recommend using no more than 2000 unique photos per project no matter which product or products you are ordering. Customers may experience an order failure if the total number of unique photos exceeds this limit.
File size is actually the limiting factor, as more than 2000 is possible provided the images are not large in file size. This problem most often affects print orders, but can occasionally occur with books.
Note: For prints, this does not mean you can't order more than 2000 prints at a time; ordering multiple prints of any of the 2000 unique images is possible. For instance, ordering 5 copies of 1000 images should not cause a problem. If you want more than 2000 unique images printed, please order them in batches.